and helps prevent cavities. go beyond brushing with act®. you never know what you might find digging underneath rome. well, how about this one? while digging rome's third metro line, archaeologists found a third century house destroyed by fire but well-preserved. >> so cool. complete with central heating systems, beams and even the bones of a dog. cnn's ben wedeman takes a step back in time with this report. >> reporter: scratch the surface in rome and you find history. it's an archaeologist's paradise. but for officials overseeing the long, delayed construction to the city's newest subway line, line c, rome's embarrassment of ancient riches is a curse that keeps on giving. while digging a shaft for the subway's tunnel near the coliseum late last year, workers